Dispersion of Knee Helical Axes during Walking after Maximal versus Resistant Strength Training in Healthy Subjects

Abstract

Knee joint stability can be estimated during functional tasks through the analysis of the helical axes (HAs) dispersion. The study aimed at investigating (1) the test–retest reliability of knee HAs dispersion during walking and (2) the effects of maximal versus resistant strength training on knee HAs dispersion during walking. Thirty healthy subjects (age: 22.6 ± 2.1 years) randomized into a maximal training (MT) group and a resistance training (RT) group underwent a 2-week quadricep– hamstring strength training at 90% or 30% of the maximum voluntary contraction, respectively. Participants walked on a treadmill with clusters of retro-reflective markers placed on thighs and shanks to detect knee kinematics with an optoelectronic system. Knee HAs dispersion was assessed using mean distance (MD) and mean angle (MA) at 1 week before training start, before and after the first training session, and before and after the last training session. Moderate to excellent reliability was found for MD and MA on the sagittal plane (ICCs ≥ 0.70). No differences over time were found for MD and MA between MT and RT. HAs dispersion indexes resulted in reliable parameters for the quantification of knee stability on the sagittal plane during walking. Maximal and resistance strength training induced no knee HAs dispersion changes during walking.